arXiv subjects

Nguyen Le Anh

Publications and source records attributed to Nguyen Le Anh.

9 recordsLinked to original sources

arXiv2026

Effect of the near-proton-emission threshold resonance in $^{11}$B on the branching ratio of beta-delayed proton emission from $^{11}$Be

Beta-delayed proton emission from neutron halo nuclei $^{11}\mathrm{Be}$ represents a rare decay process. The existence of the narrow resonance near the proton-emission threshold in $^{11}\mathrm{B}$ explains its unexpectedly high probability. However, the accurate value of the branching ratio remains challenging to determine. We aim to quantify the influence of the narrow resonance near the proton emission threshold on the result of the branching ratio. We employ the Skyrme Hartree-Fock calculation within the potential model to obtain the branching ratio. We derive the single-particle potentials for the halo neutron and the emitting proton with minimal adjustment. Slight variations in the resonance position significantly impact the branching ratio, with the upper limit reaching the order of $10^{-5}$. Experimental determination of the resonance energy, particularly whether it lies below $200$ keV, is crucial for determining the value of the branching ratio.

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arXiv2026

Long-lived opposite-parity states and the onset of octupole collectivity in atomic nuclei

Octupole deformation in atomic nuclei is of interest for both nuclear structure and precision tests of fundamental symmetries, but identifying regions of octupole collectivity remains challenging. We analyze low-energy spectra of odd-mass nuclei and uncover a previously unrecognized empirical regularity that serves as a signature of octupole collectivity in neighboring even-even systems. The observed patterns, which can be understood within a core-coupling picture, are consistent with previous theoretical studies and lead to predictions for neutron-rich and proton-deficient nuclei. These findings provide a simple empirical guide for identifying promising candidates for future experiments and microscopic calculations.

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arXiv2026

Primordial deuterium abundance from calculations of $p(n,γ)$ and $d(p,γ)$ reactions within potential-model approach

The $p(n,γ)$ and $d(p,γ)$ reactions are key nuclear inputs for Big Bang nucleosynthesis. In this work, both reactions are analyzed within a consistent two-body potential framework based on the Malfliet-Tjon interaction, including contributions from both $E1$ and $M1$ transitions. A single scaling factor $λ$ controlling the low-energy scattering dynamics is constrained by the $p(n,γ)$ and propagated consistently to the $d(p,γ)$. The obtained abundance, $\mathrm{D/H} = 2.479^{+0.350}_{-0.177}\times 10^{-5}$, is in good agreement with values inferred from metal-poor damped Lyman-$α$ systems. The modest variations of $λ$ lead to a significant change in the predicted $\mathrm{D/H}$ ratio and light-element abundances.

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arXiv2026

Low-energy $^{3}$He($α,γ$)$^{7}$Be reaction within the Skyrme potential framework

\textbf{Background:} The $^{3}$He($α,γ$)$^{7}$Be reaction plays a crucial role in the proton-proton chain and Big Bang nucleosynthesis, affecting solar neutrino fluxes and primordial element abundances. Experimental data at astrophysical energies remain uncertain due to the extremely low cross sections. \\ \textbf{Purpose:} This work uses a microscopic potential-model approach to construct the $^{3}$He+$α$ potential from the nucleon+$α$ interaction, aiming to describe low-energy elastic scattering and to calculate the astrophysical $S$ factor of the $^{3}$He($α,γ$)$^{7}$Be reaction. \\ \textbf{Method:} The nucleon-nucleus potential is derived from self-consistent Skyrme Hartree-Fock (HF) calculations extended to the continuum. The $^{3}$He+$α$ potential is then obtained by folding the HF potential with the $^{3}$He density. A small number of scaling parameters is constrained by elastic-scattering data.\\ \textbf{Result:} The scaled Skyrme HF potential and folded potential simultaneously reproduce the low-energy $p$+$α$ and $^{3}$He+$α$ $s$-wave phase shifts, respectively. The calculated astrophysical $S$ factor of $^{3}$He($α,γ$)$^{7}$Be shows good agreement with experimental data, yielding the recommended value $S_{34}(0) = 0.610 \pm 0.024$~keV~b. A moderate sensitivity of $S_{34}(0)$ to the choice of projectile density is also observed in the folding procedure. \\ \textbf{Conclusion:} The Skyrme HF-based potential provides a unified and predictive microscopic framework for describing both elastic scattering and radiative capture in light nuclei.

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arXiv2026

A global potential constrained by the Bohr-Sommerfeld quantization condition for $α$-decay half-lives of even-even nuclei

The $α$ decay provides valuable constraints on nuclear structure and plays an essential role in identifying heavy and superheavy nuclei. We study $α$-decay half-lives of 178 even-even nuclei within a semi-classical WKB framework using a phenomenological Woods-Saxon $α$-nucleus potential. The potential depth is determined by imposing the Bohr-Sommerfeld quantization condition (BSQC), ensuring a physically consistent description of the quasibound $α$-daughter system. To facilitate large-scale calculations, a global parametrization of the BSQC-constrained potential depth is constructed. The resulting half-lives reproduce experimental data with comparable accuracy for both the direct BSQC approach and the fitted prescription, providing a first step toward a global and computationally efficient description of $α$ decay.

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arXiv2026

Low-energy 17O(n,g)18O reaction within the microscopic potential model and its role for the weak r-process

The neutron radiative capture reaction $^{17}$O(n,$γ$)18O plays a pivotal role in both nuclear structure studies and astrophysical nucleosynthesis, particularly in the formation of elements during hydrostatic and explosive stellar environments. We calculated the $^{17}$O(n,$γ$)$^{18}$O cross section within the Skyrme Hartree-Fock potential model and analyzed electric dipole E1 transitions to both positive and negative-parity states below the alpha-decay threshold in $^{18}$O. Our cross sections are significantly different from the data available in commonly used libraries. We further investigate the impact of the new calculated cross section on weak r-process nucleosynthesis using large-scale reaction network calculations across a wide range of electron fractions and entropies. Our results show that the $^{17}$O(n, $γ$)$^{18}$O reaction rate significantly influences the production of first r-process peak elements, such as strontium, under specific astrophysical conditions. This study highlights the importance of accurate nuclear dat$ for light isotopes in modeling heavy-element synthesis and provides updated reaction rates for future nucleosynthesis simulations.

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arXiv2024

Magnetic dipole transition in proton-deuteron radiative capture at BBN energies within potential model

The $pd$ radiative capture reaction plays a vital role in Big Bang nucleosynthesis and stellar proton-proton chain. The study of the low-energy reaction is challenging in both experiments and theories. Using the framework of potential model, we analyze $pd$ radiative capture below 1 MeV for both electric dipole ($E1$) and magnetic dipole ($M1$) transitions. The obtained astrophysical $S$ factors agree well with recent results, especially at energies relevant to sensitive deuterium abundance. The calculated reaction rate shows good agreement, with less than a 5\% difference compared to recent works. The extrapolated value for $S(0)$ including both transitions is determined to be $0.211 \pm 0.016$ eV b. A comparison with experimental data using the $χ^2$ test reveals the sensitivity of the $M1$ cross section at low energies to the scattering potential depth.

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arXiv2021

Study of ($p,n$)IAS and ($^3$He,$t$)IAS charge-exchange reactions with the $G$-matrix folding method

Differential cross sections of ($p,n$) and ($^3$He,$t$) charge-exchange reactions leading to the excitation of the isobaric analog state (IAS) of the target nucleus are calculated with the distorted wave Born approximation. The $G$-matrix double-folding method is employed to determine the nucleus-nucleus optical potential within the framework of the Lane model. $G$-matrices are obtained from a Brueckner-Hartree-Fock calculation using the Argonne Av18 nucleon-nucleon potential. Target densities have been taken from Skyrme-Hartree-Fock calculations which predict values for the neutron skin thickness of heavy nuclei compatible with current existing data. Calculations are compared with experimental data of the reactions ($p,n$)IAS on $^{14}$C at $E_{lab}=135$ MeV and $^{48}$Ca at $E_{lab}=134$ MeV and $E_{lab}=160$ MeV, and ($^3$He,$t$)IAS on $^{58}$Ni, $^{90}$Zr and $^{208}$Pb at $E_{lab}=420$ MeV. Experimental results are well described without the necessity of any rescaling of the strength of the optical potential. A clear improvement in the description of the differential cross sections for the ($^3$He,$t$)IAS reactions on $^{58}$Ni and $^{90}$Zr targets is found when the neutron excess density is used to determine the transition densities. Our results show that the density and isospin dependences of the $G$-matrices play a non-negligible role in the description of the experimental data.

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arXiv2020

Folding model approach to the elastic $p+^{12,13}$C scattering at low energies and radiative capture $^{12,13}$C$(p,γ)$ reactions

The proton radiative capture $^{12,13}$C$(p,γ)$ reactions at astrophysical energies, key processes in the CNO cycle, are revisited in the potential model with the proton-nucleus potential for both the scattering and bound states obtained in the folding model, using a realistic density dependent nucleon-nucleon interaction. For the consistency, this same folding model is also used to calculate the optical potential of the elastic $p+^{12,13}$C scattering at energies around the Coulomb barrier. The folded $p+^{12,13}$C optical potentials are shown to account well for both the elastic $p+^{12,13}$C3 scattering and astrophysical $S$ factors of the radiative capture $^{12,13}$C$(p,γ)$ reactions.

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